transplantation

Question 1

rejection

Answer 1

damage done by immune system to a transplanted organ

Question 2

autologous transplant

Answer 2

tissue returning to same individual after a period outside body, usually in frozen state

Question 3

syngeneic transplant

Answer 3

transplant between identical twins

also called isograft

Question 4

allogeneic transplant

Answer 4

takes place between genetically non-identical members of same species
always risk rejection

Question 5

cadaveric transplantation

Answer 5

use organs from dead donor

Question 6

xenogeneic transplant

Answer 6

between different species

highest risk rejection

Question 7

criteria for solid organ transplantation

Answer 7

good evidence damage is irreversible
alternative treatments not applicable
disease must not reccur

Question 8

minimising chance of rejection

Answer 8

donor + recipient ABO compatible
recipient must not have anti-donorHLA anitbodies
donor close as poss HLA match to recipient
immunosuppression therapy

Question 9

complications of transplantation

Answer 9

graft rejection 
graft vs host disease
infection 
neoplasm 
drug side effects 
disease recurrence

Question 10

is immunosuppresion required for cornea transplant

Answer 10

no - doesnt become vascularised

Question 11

hyperacute rejection

Answer 11

within mins/hrs
preformed antibodies to ABO/HLA
antibody binding triggers TII H.S
graft destroyed by vascular thrombosis

Question 12

preventing hyperacute rejection

Answer 12

careful ABO and HLA crossmatching

Question 13

acute rejection

Answer 13

within days/weeks
TIV H.S
donor dendritic cells stimulate allogenic response in local lymph node - T cells proliferate and migrate to graft
HLA incompatibility main cause

Question 14

acute rejection vs accelerated rejection

Answer 14

accelerated: 2-5days, pre-sensitised T cells
acute: 7-21days, newly sensitised T cells

Question 15

immunology of graft rejection

Answer 15

afferent phase: donor MHC molecules on dendritic cells within graft recognised by CD4+ T cells (allorecognition)

efferent phase: CD4+ T cells recruit effector cells: macrophages, CD8+ T cells, B lymphocytes, NK cells

Question 16

chronic rejection

Answer 16

months-years
element of allogenic reaction often mediated by T cells (can result in repeated acute infection)
may be caused by recurrence of pre-existing autoimmune disease

Question 17

tolerance and transplantation

Answer 17

no response to alloantigens on transplanted tissue but response to pathogens is not affected

Question 18

tissue typing techniques

Answer 18

HLA typing

HLA cross matching

Question 19

HLA cross matching

Answer 19

B cells from donor blood (chosen as express HLA class I and II) mixed with recipient serum

ensures recipient has not made any antibodies to donor antigens

Question 20

SCT

Answer 20

heamapoeitic stem cells used to restore myeloid and lymphoid cells

Question 21

autologous SCT

Answer 21

marrow removed, frozen and reinfused after chemotherapy

minimual immunologic risk

Question 22

alllogenic SCT

Answer 22

very high risk

indications

• haematological malignancy with no other Rx options
• 1ry immunodeficiency e.g. SCID
• where myeloid cell production is reduced/notably abnormal cells e.g. aplastic anaeima

Question 23

stem cell sources

Answer 23

bone marrow: aspirated with donor under GA
peripheral blood: donor treated with colony-stimulating factors to inc number circulating stem cells
cord blood: immature lymphocytes less likely to cause reaction

Question 24

SCT conditioning

Answer 24

high dose chemotherpay
high dose radiotherapy

destroy recipient stem cells and allow engraftment of donor cells

Question 25

problems with xenotransplantation

Answer 25

• non-primate species have gal-a1,3-gal sugar side chains which all humans have antibodies against –> hyperacute rection
• xenotransplant organs activate recipient complement